Ian Thorpe has failed to qualify for the final of the 100m butterfly at the FINA World Cup swim meet in Singapore.

Thorpe finished third in his heat, recording the 11th-fastest time overall.

Thorpe finished seventh in last night's 100m individual medley final and will now turn his attention to meets in Beijing and Tokyo this week.

The five-time Olympic champion said after the medley final he was simply relieved to have returned to racing after five years out of the sport and was not too focused on results or performances.

He admitted after the race he was disappointed with elements of the swim, but said he would still take plenty of positives from the two-day meet.

"It is what it is ... I haven't swum for a long time and I've got to take stock of where I was 12 months ago to where I am now," he said.

"I'm alright, it was an OK race ... I would have liked to have made the final.

"I didn't go hard where I should have and kind of fell into an awkward technique in the race.

"But with yesterday and today, I'm pretty happy with how I've swum thus far and it's a good starting point for the rest of the World Cups.

"I'm disappointed because I thought I'd be a little bit faster this morning, I'm also disappointed because I thought some things technically could have been better."

Thorpe said the performance served as a reminder that he still had some way to go in converting his progress from training into racing.

"I think I have to have a reality of check of where I am as opposed to how I feel about how I'm training," Thorpe said.

"It's taking a step back from how I've just raced.

"If I look at this competition and how I felt three months ago, these results are fantastic, if I take it back three months ago, they're alright.

"I'm happy with the progression I'm kind of making. I haven't raced for a long time and this is the most important part of my preparation now, combining my preparation with my racing."

Thorpe, who has been training in Switzerland under star coach Gennadi Touretski, has chosen not to unveil the updated version of the famous freestyle which put him on top of the sport in the early 2000s.

While he failed to make Saturday night's final, Australians Sam Ashby (52.09) and Andrew Lauterstein (53.15) both went through behind fastest qualifier, Kenya's Jason Dunford (51.50).